Field of Invention
The invention relates to optical fibers. More particularly, the invention relates to partially bonded optical fiber ribbon structures and high speed processing methods for making partially bonded optical fiber ribbon structures.
Description of Related Art
Mass fusion splicing makes the use of optical fiber ribbons attractive in relatively very high fiber count cable structures, as this technology allows the splicing of 12 ribbonized fibers in approximately the same amount of time as is required to splice two or three individual fibers. Optical fiber ribbons are optical fibers bonded together as a (typically) flat ribbon of optical fibers. There are now market requirements for cables having at least 1000 to 5000 optical fibers.
The cabling of conventional flat optical fiber ribbons becomes more problematic as the number of flat optical fiber ribbons being cabled increases. Conventionally, flat optical fiber ribbons are grouped into rectangular arrays, often referred to as stacks, and positioned within a cable structure. However, optical fiber cables usually need to be circular to be easily installed. Thus, the square peg, i.e., the rectangular ribbon stack, must fit in the round hole, i.e., the circular cable structure. Such conventional configurations lead to empty space in the cable structure.
Some existing optical fiber cable manufacturers have developed a partially bonded optical fiber ribbon, also referred to as a rollable ribbon, where the optical fibers forming the optical fiber ribbon are not bonded over their entire length. The optical fibers are bonded intermittently, thus allowing the optical fiber ribbon to be folded or rolled into an approximately cylindrical shape, allowing for better filling of the circular cable, resulting in more optical fibers to be included in a given cable diameter compared to optical fiber cables with conventional fully bonded ribbon structures.
However, conventional methods for producing partially bonded optical fiber ribbon structures often are more complex than conventional methods for producing conventional flat optical fiber ribbon structures. For example, in conventional methods for producing partially bonded optical fiber ribbon structures, the application or placement of the bonding agent (i.e., bonding matrix material) at proper locations on the optical fiber ribbons, as well as the proper amount of bonding matrix material that needs to be applied to the optical fiber ribbons, are relatively difficult to determine compared to conventional methods for producing flat optical fiber ribbon structures because the location and amount of bonding matrix material used in producing partially bonded optical fiber ribbon structures greatly affects the integrity of the partially bonded optical fiber ribbon structures.
For example, improper placement of the bonding matrix material on an optical fiber ribbon often leads to inadequate bonding between adjacent optical fibers, resulting in an unsuitably loose partially bonded optical fiber ribbon structure. Also, an insufficient amount of bonding matrix material applied to an optical fiber ribbon often causes the resulting partially bonded optical fiber ribbon structure to have too many loose optical fibers. However, applying too much bonding matrix material to an optical fiber ribbon often causes the resulting partially bonded optical fiber ribbon structure to become too rigid, thus making the structure relatively difficult or even impossible to roll or fold adequately for compact packaging within a cable structure. Because of these difficulties associated with conventional methods for producing partially bonded optical fiber ribbon structures, processing speeds and ribbon structure fiber counts typically are relatively low compared to methods for producing conventional flat optical fiber ribbon structures. For example, many conventional methods for producing partially bonded optical fiber ribbon structures typically can only produce 8-fiber or less partially bonded optical fiber ribbon structures.